Birger ljungstrom



No Model.)

B. LJUNGSTROM. CHAIN DISK 0R CAM FOR BIGYGLES.-

N0. 599,851. Patented Mar. 1, 1898.

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' Nrrnn STATES ATENT FFICEQ CHA IN DISK OR CAM FOR BlCY-CLES.

SPECIFICATION formingpart of Letters Patent No. 599,851, dated March 1, 1898.

Application filed J l 1, 1897. S ial No, 643,060. (No model.) Patented in Sweden May 4,1895, No. 6,346; in Germany June 11,1895, No. 87,538; in England August 13, 1895, No. 15,280; in France September 16, 1895,1T0. 250,307; in Belgium September 24, 1895, 110,117,594; in Austria December 25, 1895, N0. Pi/5,130; in India December 28, 1895, No. 415 {in Italy December 81, 1895,11), 40,083/386; in Spain January 2, 1896,1Io. 18,186; in Hungary January 14, 1896, No. 5,202; inVictoria February 12,1896, No. 12,881; in South Australia February 18, 1896,110. 3,172; in New South Wales February 14, 1896,1To. 6,389, and in New Zealand February 21, 1896,110- 8,Z88.

To and whom it may concern.-

vBe it known that I, BIRGER LJUNGsTR5M, mechanician, a subject of the King of Sweden and Norway, and a resident of Grefgatan 44b, Stockholm, in the Kingdom of Sweden, have invented certain new and useful Improvements in Chain Disks or Cams in Bicycles and other Vehicles, of which the following is a specification, reference being had therein to the accompanying drawings.

This invention has been patented to me in the following countries: Sweden, No. 6,346, dated May 4, 1895; Germany, No. 87,538, dated June 11, 1895; France, No. 250,307, dated September 16, 1895; Great Britain, No. 15,230, dated August 13, 1895; Belgium, No. 117,594, dated September 24, 1895; Austria, Band Seite 5,130, dated December 25, 1895; Hungary, No. 5,202, dated January 14, 1896; India, No. 415, dated December 28, 1895; Victoria, No. 12,881, dated February 12, 1896; New Zealand, No. 8,288, dated February 21, 1896; NewSouthWales,No. 6,389,dated February 14, 1896; South Australia, No. 3,172, dated February 13, 1896; Spain, No. 18,186, dated January 2, 1896, and Italy, N0. 40,083/386,

dated December 31, 1895.

The driving mechanism of bicycles and other vehicles having oscillating treadles, which, by means of chains, ropes, or the like, are connected with ratchet-couplings actuating the driving-wheel, includes disks or cams mounted near the wheel and which alternately wind on and off the chain or rope.

This invention relates to such a disk or cam which differs from others used for the purpose in being of helical or scroll shape, so as to be able to wind on or off more than one turn, and in being at the same time eccentrio in such a manner as to have its maximum radius perpendicular to the chain when the treadle is in its middle position. When the treadle is at its turning-points, a short being at its maximum when the treadle is in its middle position.

Figure 1 is a side view of a bicycle of the kind referred to. Figs. 2 and 3 show a side view and a top view, respectively, of the cam or scroll. Fig. '4 is a vertical section of the scroll. Fig. 5 is a transverse section of the ratchet-coupling.

From the treadle 1 the driving-chain 2 runs to the scroll 3, mounted on the axle or hub of the driving-wheel. 5 in Fig. 5 represents the hub of the scroll, said hub bearing upon the rollers 6 of the ratchet-coupling. The rollers in well-known manner carry the drivingwheel axle or driving-wheel hub along when the scroll rotates in one direction; not when it returns, however. The scroll consists of a ring which, viewed from one side, has the shape of a spiral starting from and again returning to the center, as shown in Fig. 2, and, viewed endwise, is shaped as a helix, Fig. 3. Said ring, which is of grooved section for receiving the driving-rope 2, embraces the hub 5 with its ends 8 15 and is further supported by the arm 9, projecting from the hub and connected with the widest part of the scroll. At the points of contact ring and hub and ring and arm are suitably connected by rivets or the like. On the arm 9 there is a small lug or projection 10, on which is mounted a ring 11. The driving-rope 2, starting from the treadle, enters the scroll at 14 and following along it to 15 continues in'a loop around the ring 11, to which it is soldered or otherwise fastened. When the treadle is in motion, the rope is alternately wound on and off the scroll 2. The position of the latter in Fig. 2 corresponds to the middle position of the treadle, and it may be seen that in this position the chain acts upon the driving wheel with its maximum turning moment, and that the turning moment decreases, whether the treadle be moving toward the upper turning-point or the lower one. While the treadle moves from one of these points to the other, the scroll revolves nearly one and one-half turn, this being made possible by its helical shape, Fig. 3. The return movement is effected by means of a separate rope passing over the pulley l6 and special pulleys 12 on the hubs 5. (Not shown in the detail figures.)

Having now described my invcntion,what I claim asncw, and desire to secure by Letters Patent, is

1. In bicycles and other vehicles, the combination, with oscillating treadles 1 and reciprocating chains or ropes 2, of cams or scrolls, adapted to wind the chains or ropes alternately on and off more than one turn, and shaped as helices of varying radii, so as to cause the turning-moment of the chain acting on the driving-axle, to decrease toward both ends of the stroke of the chain, substantially as shown and set forth.

2. I11 bicycles and other vehicles the combination with oscillating treadles 1 and reciprocating chains or ropes 2, of cams or scrolls 3 adapted to wind the chains or ropes alternately on and off and consisting of a helically-shaped ring, mounted eccentrically with reference to the driving-axle in such a manner that its two ends approach the latter, a hub 5, embraced by the said ends, and an arm 0 projecting from the hub and supporting the portion of the ring farthest removed from the hub, substantially as shown and set forth.

3. I11 bicycles and other vehicles, the combination, with oscillating treadles 1 and reciprocating chains 2, of a helical chain cam or scroll 3, eccentric with reference to the driving-axle, a hub 5 for said cam or scroll, and an arm 9 connecting said hub with the cam or scroll and to which the chain or rope carried around the scroll is attached.

In witness whereof I have hereunto signed my name in the presence of two subscribing witnesses.

BIRGER LJUNGSTROM.

Vitnesses:

ERNsT SVANGVIST, HANS B. OI-ILSSON. 

